Scanner Reveals Secrets of Ancient Documents

Photonics.comOct 2011
OXFORD, England, Oct. 3, 2011 — A scanner developed at the University of Oxford’s Classics Department is being commercialized by a new company — Oxford Multi Spectral Ltd. — spun out last week by the university’s technology transfer company.

Developed for imaging ancient papyri, the new device has been used to successfully scan, restore and archive more than a quarter of a million historically significant manuscripts.

A multispectral scanner created at Oxford University was developed to image ancient papyri but has modern uses as well. (Photos: Oxford Multi Spectral Ltd.)
Oxford Multi Spectral will focus on the applications in restoring manuscripts and art as well as on the huge potential market for detecting forged security and border control documents, banknotes and forensic evidence.

The scanner could be used to analyze a huge variety of samples, including those from a crime scene such as counterfeit and altered documents or documents bearing erased or faded entries and signatures, said Paul Westwood, managing director of Forensic Document Services, the biggest forensic document company in the Asia Pacific.

Alexander Kovalchuk, the physicist who invented the Oxford multispectral scanner.
“The portable nature of the scanner means that it will be a great resource when document examiners are required to undertake examinations out of the laboratory environment, such as at court registries or the offices of opposing lawyers,” he said. “We anticipate that using the Oxford scanner will be like moving from using a darkroom to using a modern digital camera. We can use it to detect what is currently invisible and make it visible.”

Current multispectral imaging kits use cameras, but they are large and expensive and require specialist operators. The Oxford device uses flatbed scanner technology and powerful image processing to scan visible and “invisible” features that absorb and reflect light at different wavelengths, such as inks, pigments, polymers or papers.

[L to R]: Mike Broderick, CEO of Oxford Multi Spectral Ltd.; Dirk Obbink, University lecturer in papyrology; and Alexander Kovalchuk.
“An ordinary color image has three layers: red, green and blue; a multispectral image has many more layers, some of which are invisible to the human eye, but all of these layers contain potentially useful information,” said Alexander Kovalchuk, the physicist who invented the scanner. “Our scanner is capable of registering an unlimited number of layers.”

The technical leaps incorporated in the scanner’s design mean that ancient documents that once were unreadable now can be scanned and read, added Dirk Obbink, the head of the research group that developed the device.

The Oxford Multi Spectral scanner can be used to detect forged banknotes.
“We can take digital images at different wavelengths of the light band and layer them on top of each other, using software to analyze them,” Obbink said. “We can set the equipment to interrogate a feature we are interested in: the surface structure, fibers, stains, watermarks, fingerprints or alterations. We can detect an artist or writer’s signature under multiple layers of paint or the pencil sketch under a watercolor.”

Oxford Multi Spectral has secured an investment of £250,000 (about $388,000) from Changsha Yaodong Investment Consulting Co. of China and its UK-based partner, RTC Innovation Ltd. of Birmingham to commercialize, manufacture and market the scanners globally. It received £47,600 (about $74,000) from the University Challenge Seed Fund last year for prototyping work.

Multispectral Imaging: Creation of an image where each pixel contains more than three spectral data points, typically four to 20. This is contrasted with a standard color camera that only captures three spectral data points (called RGB), or hyperspectral cameras, which capture hundreds of spectral data points. Traditional multispectral cameras captured four data points: RGB and an NIR band. Nowadays multispectral cameras are available as commercial off-the-shelf products, with 12 custom bands...